Hard Industrial Chroming of Aluminum, Brass or Steel Cylinders

[julianconde]

I have received several requst about the possibility of chroming various size cylinders. The standard cost of chroming a cylinder is approximately $50.00. This would include the finish honing process but does not include the cost of the various sizes of holding fixtures required. There is also the problem with removing the chrome from aluminum cylinders which can only be done by grinding the chromed surface down to the original aluminum surface. Removing chrome from brass involves placing the brass cylinder in a 50% solution of HCL. Therefore, from a cost consideration, the possibility of chroming anything except the production cylinders used in our engines would be out of the question at this time.

Jim Allen

Do

You still have some Nelson engine parts ??

 

[Jim Allen]

Julian,

I only have parts for the Q-40 & the Q-500 long stroke pylon racing engines. I have some parts for my FAI .45 long stroke tunnel hull engine, but I will need these. I sold all of parts to the FAI .45 long stroke engines, mounts & curvy tuned pipes.

JA

 

[Jim Allen]

I have continued to receive private E-mails concerning the chemicals used to prepare aluminum cylinders for chroming. A decision is being made as to when & if we will release this information to the public at large. The process that we have in place at present allows the chrome plating to be done in + or - .0001" amounts. Before honing the plated surface is very smooth, allowing very rapid honing to a finished product.

Jim Allen

 

[Jim Allen]

We have been very busy lately building up our cylinder inventory. Further improvements to our chroming process has reduced the chroming time to 63 minutes at 12.7 amps for each cylinder. Stabilizing the chrome bath's temperature (120* to 126* F) has been proven to be necessary from startup to finish.

JA

 

[Jim Allen]

The photos show the custom designed tools required to make positive contact when connecting the power supply to the chrome tanks anode & cathode. Failure to make a positive contact at any point will result in excessive heat being generated at that point because the tank is operating at approximately 13 amps for approximately 63 minutes. More information will be released about the chemicals & how they are to be used when we finish consulting with our attorneys. These chemicals can be dangerous if used without thought by a "CHICKEN HEAD"!!! No offense intended. LOL!

Jim Allen

 

[Jim Allen]

New heavy duty, flint glass, round, 6" OD X 7-3/4" high battery jars from Flinn Scientific at a cost of $50.00 each, including shipping will be used for the new chrome tanks. New holding, masking fixtures will be used to chrome steel, brass & aluminum cylinder ID's. New battery jar covers were machined to fit both the old & new type battery jars. More details to follow on how to reverse the current when etching steel cylinders before chroming.

Jim Allen

 

[Terry Keeley]

Great system!

 

[Brian Spitzer]

Jim,

What material do you use to machine the covers from?

 

[Jim Allen]

Brian,

PVC can be used for any plastic part in the chrome tank. Brass parts should be made from #360 free machining brass. Alligator clips are Mueller 25C 75-amp types with 25C rubber insulators.

JA

 

[Brian Spitzer]

Jim,

From post 165, has a decision been made on releasing more information on the plating process?

 

[Terry Keeley]

I looked up my notes from 20 years ago, I used the formula that's all over the net and what Caswell plating recommends:

https://www.caswellcanada.ca/hard-chrome-plating/

I used "Chromium Trioxide" crystals (UN1463), the sulphuric acid was 1.84 SG (98%+), plus distilled water.

Bath temp was 50C, current density was 2.5 A/sq in, about 10A for a 45 liner and 14 for a 67.

I might try to chrome some 67 cranks this winter in the area of the rear bearing to improve the fit.

 

[Brian Spitzer]

Thank you Terry! A 25 Amp power supply should be more than sufficient?

 

[Terry Keeley]

Thank you Terry! A 25 Amp power supply should be more than sufficient?

Oh ya. Be sure the parts are very (chemically) clean, I used a 15% sodium hydroxide solution for a 5 min soak.

 

[Jim Allen]

Brian,

The "SUCCESSFUL" hard industrial chroming of any type of brass alloy only requires a general physical cleaning & then a chemical cleaning in a strong alkaline solution. However, the "SUCCESSFUL" hard industrial chroming of aluminum is a very different situation! Aluminum alloys must be carefully cleaned physically with Dawn, a rotating brush & hot water. The cylinder is then "immediately" placed in three different chemical baths, for a specific measured amount of time for each bath. In between each bath, the cylinder is washed in hot running water. After the final immersion in the last bath, the cylinder is washed in hot running water & then it is "immediately" placed in it's chroming fixture. MISS ANY STEP IN THIS PROCEDURE & YOU WILL HAVE A PITTED, FLAKING OFF, NOT HARD, CHROME PLATE!

The typical basic Chromium Trioxide bath should be operating at 125 to 130* F. The bath's temperature & current density will affect the hardness of the chrome plate. A typical .45 size liner will run at 13.5 amps for 58 minutes providing the electrical contacts between the cylinder, the anode, the cathode & the power supply are "absolutely sound". This current & time will put on approximately .0015" of chrome per side. Any bad connection anywhere will generate unwanted heat & raise the necessary current density amount! The power supply should be as ripple free as possible. The power supply should have an adjustable current & voltage output. There should be a precision amp meter & volt meter between the power supply & the chrome bath. A typical basic chromium bath will plate approximately 200 cylinders.

As previously stated the necessary chemicals used for aluminum alloys are very corrosive & dangerous! The chrome tank emits very heavy fumes when in operation & it should be operated in a controlled environment. No decision has been made concerning the release of information about the chemicals being used.

Jim Allen

 

[Terry Keeley]

Brian,

The "SUCCESSFUL" hard industrial chroming of any type of brass alloy only requires a general physical cleaning & then a chemical cleaning in a strong alkaline solution. However, the "SUCCESSFUL" hard industrial chroming of aluminum is a very different situation! Aluminum alloys must be carefully cleaned physically with Dawn, a rotating brush & hot water. The cylinder is then "immediately" placed in three different chemical baths, for a specific measured amount of time for each bath. In between each bath, the cylinder is washed in hot running water. After the final immersion in the last bath, the cylinder is washed in hot running water & then it is "immediately" placed in it's chroming fixture. MISS ANY STEP IN THIS PROCEDURE & YOU WILL HAVE A PITTED, FLAKING OFF, NOT HARD, CHROME PLATE!

The typical basic Chromium Trioxide bath should be operating at 125 to 130* F. The bath's temperature & current density will affect the hardness of the chrome plate. A typical .45 size liner will run at 13.5 amps for 58 minutes providing the electrical contacts between the cylinder, the anode, the cathode & the power supply are "absolutely sound". This current & time will put on approximately .0015" of chrome per side. Any bad connection anywhere will generate unwanted heat & raise the necessary current density amount! The power supply should be as ripple free as possible. The power supply should have an adjustable current & voltage output. There should be a precision amp meter & volt meter between the power supply & the chrome bath. A typical basic chromium bath will plate approximately 200 cylinders.

As previously stated the necessary chemicals used for aluminum alloys are very corrosive & dangerous! The chrome tank emits very heavy fumes when in operation & it should be operated in a controlled environment. No decision has been made concerning the release of information about the chemicals being used.

Jim Allen

I'm sure the process for successfully plating aluminum must have taken many, many hours to perfect. Many other manufacturers have had problems with the plating on their aluminum liners and have gotten away from them, the weight advantage must be worth the effort in pylon racing tho.

I also successfully plated some cast iron liners for my buddies 1/4 scale V8 and that was much more difficult than chrome, brass is a breeze to plate!

 

[Jim Allen]

Weight is not the only advantage when using the correct aluminum alloy for the cylinder. The 4032 aluminum alloy used for the cylinder, combined with the hard industrial chrome plate expands at a rate that is slightly larger than the RSP-444 piston alloy. This fact plus the correct amount of taper on the piston & in the liner make it impossible for the engine to seize, even when over leaned!

Jim Allen

 

[Rudy Formanek]

Knew a guy that tried doing chrome plating in his garage (1980's). The fumes etched his wife's car's windshield. He almost got divorced over that. A hammer left on the workbench rusted badly. Ron Sheldon (1970's) used to do it in a separate out-building. He was building Supertiger G-40's for RC airplane F-1.

 

[Jim Allen]

Rudy,

The fumes that come out of a typical 1 gallon size tank, operating at 130* F, will fill a 3 car size garage in several minutes. Anything that is made of steel or iron, even pieces that have been hardened, will be rusted in a matter of minutes. Any electrical circuit which is not in a sealed container will also be damaged. This is one reason we are reluctant to divulge what chemicals are to be used in chroming aluminums.

JA